The objective of this proposal is to obtain continuing support for the Harvard Medical School Research Center in Radiologic Imaging and Diagnosis in which radiologic tools in conjunction with other physiologic, pharmacologic, morphologic, biochemical, and biophysical methods are creatively applied to the solution of biomedical problems. The Center supports a nucleus of investigators in a broad, continuing program oriented toward understanding and advancing our knowledge of all elements of radiologic science, imaging, the diagnostic process, and the underlying pathophysiology responsible for normal and abnormal radiologic images. There is a special emphasis on the regional circulations in mammals. The Center also provides a well-equipped research facility sufficiently versatile and flexible to respond quickly to new and promising directions in research undertaken by faculty and trainees alike. Because there are many combined basic laboratory and clinical research projects already underway, a particular objective of the Center is the rapid transfer of advances made in the laboratory to the clinic. Furthermore, the multidisciplinary and multifaceted approaches to problems provide an objective measure for the interpretation of data obtained with radiographic methods. In the process of developing its research potential, the Center also serves as a training resource for investigators and academic radiologists drawn particularly from the Harvard departments and from the medical schools of the New England region.